Articles Taggés ‘DPGS’

SMOS L2 soil moisture reprocessing finished and ready

27 février 2012

Dear All

Last Week the SMOS level 2 data reprocessed at CNES by CESBIO was officially accepted by ESA after validation. The data set is now being shipped to ESA and Brockman for dissemination.

reprocessed global-2012

The new processor is close to the previous one (level 2) but with an improved Level 1. With this reprocessing and, following, the routinely processed data, it is now 26 months of uniformly processed data which is available (and counting!)

The answer…. to the quizz

1 septembre 2011

Yes, as most of you found out, it is an Iceberg (not that big wrt SMOS resolution, but large never the less)
Ewa Slominska gave me the following pictures with the blog post the other day…
The Area where the point was travelling looks like this at the time of SMOS over pass closest to the ENVISAT ASAR overpass.

iceberg-smos and if we super- impose SAR data we get…
iceberg Bingo! actually zooming a little more we see the iceberg
iceberg-zoom It is not that big!
More details on this link provided by Serge and Fernando at ESAC
http://www.natice.noaa.gov/pub/iceberg_images/jpeg/2011233_B15J.jpg

SMOS catches rare events

13 mai 2011

By Joaquin Munoz Sabater (ECMWF) and Fernando Martin Porqueras (IDEAS)

The 18 of April 2011 a strip with unusual values of brightness temperatures was detected in Western Sahara and Morocco. This feature looked strange enough to the Quality Check team Given at ESAC that they asked US what we thought about it. Many options were quickly discarded (RFI, Instrument problem etc…). The problem was that the measurements as shown on the QC picture below pointed towards high soil moisture which is not all that expected at this period of year in this area with such a linear shape.

morocco

Fig 1 QC picture on two orbits (Ascending and Descending) on April 18th 2011 from DPGS (X pol on the left and Y on the right)

However, between the 17 and 19 April 2011 a rare precipitation event took place in Western Sahara. Precipitations up to 10 mm, locally stronger, took place in a narrow, well defined band through the desert. This was caused by the influence of a low placed in the Azores which produced unusual precipitations in the Sahara area. This precipitation band moved progressively towards the North-East direction. Figures 1-4 show the cumulated total precipitation during 48 hours, in steps of 12 hours, starting the 16 April 2011. These figures clearly show the direction and cumulative values of the precipitation band. Non-coincidentally, there is a very good correlation between SMOS measured brightness temperatures (being much colder than its surroundings) and these precipitation figures, which explain these abnormal values. Figure 5 shows the ECMWF soil moisture analysis the 18 April 2011 at 12h00, for the first layer (7cm), which also displays this geographical strip being wetter (up to 20%) than its very dry surroundings. SMOS was able to catch very well this precipitation event.

step48 step49
step50 step51
SM1 SM2

These results demonstrates once more the good skills of the SMOS instrument to clearly catch rare precipitation events.

SMOS L2 data is reprocessed!

25 février 2011

At long last and after several glitches L2 Soil moisture reprocessing is over!
As you may be aware, ESA reprocessed level 1C with a fixed calibration (finished in January 2011) but could not reprocess level 2 in a timely fashion (typically November 2011) as it would have required on their system – assuming it was operational- anything between 4 and 6 months, i.e., too late wrt the general reprocessing. Hence the idea to wait for the official reprocessing in LTA facilities once they are operational, which implies a end of 2011 start.

So it was decided with ESA that the reprocessing would be done by CESBIO, using the reprocessed level 1C and the V4 of le Level 2 soil moisture algorithm configured exactly as it would be at DPGS (to ensure same format and consistent data set) and this on the CNES computing facilities. Ocean group was not interested in reprocessing just now incidentally, so it concerns only soil moisture.

François was fully in charge of this mammoth task!

Here is were we are today:
1) all data from DPGS L1C has been ingested.
* L1C data has been tested over DOME C and corresponds extremely well to ground measurements (see post on January 30 2011)
* the L2 SM V4 processor worked like a charm and all data has been processed as of yesterday evening

2) A few numbers…

We have processed
* 9377 L2 products (including 7394 Fully polarised) for the period ranging from 12/01/2010 to 26/12/2010.
* which corresponds to 714345863 nodes with roughly 77% leading to a retrieval
* this used up 38858cpu hours  (1600 days!!), and 46TB of memory(on average 4h and 5Go per product).
* input data takes up 3.2TB and outputs 1.4TB

3) We started the processing on 07/01/2011, (47 days overall) with 3 stops
- from 20/01 to 25/01 (5d) test in the CNES Computing building
- from 02/02 to 04/02 (3d) link to mass storage access issue (space where all the data was stored)
- from 09/02 to 15/02 (7d) as we were still waiting for the DPGS reprocessed L1c  data  finished on 18/01 at ESAC, which also disrupted the parallel processing
So the whole task took 31 days and,should the last batch from DPGS had been delivered in January (so as to have the 6 processes running at the same time but only shifted slightly), we can reasonably say that it would have taken 25 days (François’  first estimate!).

Now while François is resting a little (well .. doing something else), we are now intensively checking the outputs
In parallel Philippe used the Prototype to run tests on smaller data sets (USA, Africa and Australia) with a large number of algorithm versions and / or configurations  (309, 410 , dual in full vs full , with and without currents etc) we are comparing all the stuff (and it takes time and people!)
conclusions -very preliminary we still have lots to do, are very encouraging and we can safely state now that we realised that we had made a couple of blunders at the beginning (to much haste!) which means that the results are probably slightly less good than they could be, but up to now (we still have a fair bit to analyse) results look fine. A bit more « noisy » maybe, especially Tau but closer to field measurements and more realistic.

To make a long story short improvements!

We are now very busy checking everything and hope to be able to show many things at the quality working group getting the green light for dissemination to you all through ESA’s usual accesses of this ESA/CNES CESBIO reprocessed levels 1C and 2 SM.

More on this next week with results … stay tuned.